Mask Material Surface Roughness for Plasma Dicing
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Solution Overview
Problem
The existing plasma dicing methods for semiconductor chips face challenges such as microscopic cracks, reduced yield due to kerf width limitations, and increased production time, along with the need for additional processes like photolithography and laser mask removal issues.
Innovation Solution
A mask material with a surface roughness of 0.1 μm to 1.5 μm and a mask-integrated surface protective tape containing a resin and ultraviolet absorbers, such as triazine or benzophenone skeletons, is used for plasma dicing, allowing for effective laser cutting and plasma ashing without residue, eliminating the need for photolithography and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blade dicing method is used to cut the semiconductor wafer, then the cutting process is simple and direct, but microscopic cracks and chipping occur in the semiconductor chips due to cutting resistance
Solution Approach 1:
The patent replaces the mechanical blade cutting system with a plasma dicing system that uses plasma to etch and separate the semiconductor wafer. This substitution eliminates direct mechanical contact and cutting resistance, thereby preventing microscopic cracks and chipping while maintaining manufacturing efficiency
2Ease of manufacture
If a thick blade is used for dicing, then the cutting process is straightforward, but the kerf width cannot be reduced below the blade width, decreasing chip yield
Solution Approach 1:
The patent replaces mechanical blade cutting with plasma dicing, allowing the kerf width to be controlled by the plasma beam diameter rather than blade thickness. This enables much narrower kerf widths, increasing the number of chips that can be obtained from each wafer while maintaining process simplicity
Solution Approach 2:
The patent changes the controlling parameter for kerf width from mechanical blade dimensions to plasma process parameters (gas flow, power, focus). This allows flexible adjustment of kerf width to optimize chip yield without being constrained by physical blade dimensions
3Manufacturing precision
If photolithography is used to form a mask for plasma dicing, then precise mask patterns can be achieved, but additional process steps and facility requirements increase device complexity
Solution Approach 1:
The patent combines the surface protective tape function with the mask function into a single integrated component. The tape is applied to the wafer surface and directly serves as the mask for plasma dicing, eliminating the need for separate photolithography mask formation and reducing facility requirements
Solution Approach 2:
The surface protective tape is given multiple functions: it protects the wafer surface during handling and processing, and simultaneously serves as the mask for plasma dicing. This multi-functionality reduces the number of separate components and process steps required
4Strength
If a smooth mask material surface is used, then the mask material adheres well to the wafer, but laser cutting efficiency is reduced due to poor laser absorption
Solution Approach 1:
The patent applies different surface qualities to different regions of the mask material. The area in contact with the wafer maintains smoothness for good adhesion, while the top surface has increased roughness to enhance laser absorption and improve cutting efficiency
Solution Approach 2:
The patent modifies the optical properties of the mask material surface by creating a rougher top surface that appears darker and absorbs laser energy more effectively. This surface modification changes the material's interaction with laser light from reflection to absorption, improving cutting efficiency
5Reliability
If conventional mask materials are used for plasma dicing, then the mask provides adequate protection, but mask removal by laser irradiation leaves residues and requires additional cleaning steps
Solution Approach 1:
The patent modifies the chemical composition and physical structure of the mask material to change its response to laser irradiation. The material is designed to undergo controlled decomposition or phase change when exposed to laser, enabling complete removal without residues and eliminating additional cleaning steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise cutting and removal of the mask material, reducing defects and production time, while enhancing the yield and quality of semiconductor chips by improving laser absorption and plasma protection.
Implementation Method 1
the parallel ray absorption rate in the wavelength of 355 nm to 10800 nm of the mask material layer is 50% or more
Implementation Method 2
a plasma dicing method of dividing a semiconductor wafer, by selectively etching a portion which is not covered with a mask, using plasma
Implementation Method 3
a mask-integrated surface protective tape containing a resin and ultraviolet absorbers, such as triazine or benzophenone skeletons
Data Source
AI summary
A mask material for plasma dicing, which is used in a plasma step, whose surface roughness Rz at the surface side that does not touch with an adherend is from 0.1 μm to 1.5 μm;a mask-integrated surface protective tape; anda method of producing a semiconductor chip.